Canopy method for hydrocarbon recovery



Dec. 13, 1966 D. P. NICHOLS CANOPY METHOD FOR HYDROCARBON RECOVERY Filed June 15, 1964 a ...fa

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DEAN P. NICHOLS FIG.

ATTORNEY United States Patent O 3,291,215 CANPY METHOD FUR HYDROCARBON RECVERY Dean P. Nichols, Dallas, Tex., assigner to Mobil Oil Corporation, a corporation of New York Filed .lune 15, 1964, Ser. No. 374,898 17 Claims. (Cl. 166-36) This invention relates to a method for recovering hydrocar-bons from subterranean carbonaceous deposits. More particularly, this invention relates to a method for recovering hydrocarbons from such deposits by in situ combustion.

There are vast carbonaceous deposits adjacent the surface of the earth from which hydrocarbons, as a result of their immobility, cannot 4be recovered by petroleum producing procedures. Examples of such deposits are the tar sands in Canada and the oil shales in Colorado. The nature of these deposits requires that the carbonaceous materials be first treated to release the innate hydrocarbon before it can be recovered from the substratum. For example, the deposits may be mined and thereafter the extracted materials treated at the earths surface to facilitate recovery of the contained hydrocarbons. The cost of mining such deposits contributes about half the cost for recovering the hydrocarbons contained therein. Alternatively, some in situ procedure for releasing and removing the hydrocarbons from the deposits may be used. As to in situ procedures, the relatively low natural permeability to fluids of these deposits prevents ready application of such procedures, especially in situ combustion, for freeing the hydrocarbons contained in such deposits so that it may be recovered. The desired permeability for in situ procedures may be created artificially; such as by hydraulic fracturing. However, in such deposits, especially in oil shales, artificially produced fractures tend t close by swelling or the like during in situ combustion so that fluid permeability is lost and the combustion operation is restricted severely or even terminated. This increases the costs for recovering the desired hydrocarbons,

It is the main object of this invention to provide a method to be applied in situ to such carbonaceous deposits, which method includes in situ combustion, without the difficulties encountered in conventional procedures as above set forth. Another object of the present invention is to provide a method for recovering hydrocarbons from subsurface carbonaceous deposits of the type described. Yet another object of the present invention is to employ the swelling of artificial fractures to advantage so as to obtain a more uniform heating of large masses in the deposit, especially in oil shales. Another further object is to provide a method of the character described in which the recovered hydrocarbons have been extensively thermally cracked so as to provide a more pumpable fluid. These and other objects will lbecome more apparent when read in lconjunction with the following detailed description, the appended claims, and the attached drawings wherein like substances -bear like characters and in which:

FGURE 1 is a fragmentary section taken vertically through a carbonaceous deposit illustrating a practice of the present method;

FIGURE 2 is a section similar to FIGURE 1 after the deposit has been uplifted to increase its volume; and

FIGURE 3 is a vertical section taken through the derice posit illustrating a system by which several steps of the present method may be practiced.

This invention is a method in which a portion of the carbonaceous deposit adjacent the surface of the earth is uplifted until its volume increases and such uplifting disrupts the surface of the earth thereabove. A combustion front is created in situ at the lower extremities of the uplifted portion of the deposit and passed upwardly by direct in situ combustion to retort hydrocarbons from the -carbonaceous material in such uplifted portion. The hydrocarbons freed by in place retorting are recovered from the iiuids expelled above the earths surface from the uplifted portion of the deposit. Other steps may be utilized, to provide further advantages, as will be apparent from the following description of this invention.

In FIGURE l, a subsurface carbonaceous deposit 11 is shown adjacent the surface of the earth and which extends to some depth within the earth. The deposit 11 may be covered by a thin overburden but preferably has its upper surface 12 exposed. The deposit 11 may be of any type having hydrocarbons which cannot be removed by petroleum producingprocedures. For purposes of description, the deposit 11 is oil shale. The deposit 11 generally cannot be directly subjected to conventional in situ combustion procedures for releasing the contained hydrocarbons because of its inherent properties. Oil shale usually has a permeability much like glazed porcelain and heat conductivity much the same as a re brick.

Therefore, the permeability of the deposit 11 is increased by the first step in an illustrative embodiment of this invention. This step is the uplifting of a portion of the deposit 11 until its volume increases and such uplifting disrupts the surface of the earth thereabove. Any means to obtain such uplifting may be used. However, the following uplifting means have great utility and advantage in this invention. For this result, a well 13 is formed downwardly from the surface 12 of the deposit 11 to a suitable depth. For example, the well 13 may extend to depths of about feet. A tubular liner 16 is positioned within the well 13 and sealed in place by any means such as cement 17. lt will be noted that the liner 16 does not extend to the total depth of the well 13. This provides a region at the bottom of the well 13 in which explosives 14 are placed. The bottom of the well 13 may be enlarged to receive the explosives 14 if desired. Thus, the explosives 14 are positioned `a vertical distance within the deposit 11 below its surface 12. The distance below the surface 12 where the explosives 14 reside may be predetermined, as will be hereinafter described. The explosives 14 may be of any type. For example, a fertilizer-grade ammonium nitrate premixed with diesel oil is well suited as the explosives 1d. A.y primary charge, such as a stick of dynamite 13, is disposed within the explosives 141i. Means for igniting the dynamite 18 are extended upwardly through the liner 16 to the surface 12. Such means may be provided by an electrical lblasting cap (not shown) carried in the dynamite 13. Such cap is connected to a battery l through a switch 21 by electrical conductors 22. The liner 16 is at least partially filled with a tamp such as a sand 25 resting upon the top of the explosives 14 and extending upwardly a short distance into the liner 16. Generally, the explosives 14 are used in such amount, and at such depth below the surface 12, that when exploded the force will uplift a portion 23 of the deposit 11 a short distance without blowing the liner 16 or the adjacent portion of the deposit completely from the deposit 11. By this method, the uplifting creates an arching of stratum upwardly and forms a mass of rubble in the portion 23 of the deposit 11. Of course, the portion 23 of the deposit 11 will slightly subside after being uplifted a short distance, but yet leave such portion with an increased volume.

Referring for greater detail to FIGURE 2, the switch 21 is closed, detonating the explosives 14 within the well 13. The resultant forces combining a detonating and compression wave effect move upwardly through the deposit 11, uplifting a portion 23 in an arching movement sufficiently to disrupt the surface 12 thereabove. As a result of uplifting, the portion 23 is comprised of a large mass of fractured rubble slightly extending above the surface 12. Preferably, the portion 23 is uplifted sufiiciently to increase its original total volume by not over percent. Such increase in volume provides sufficient permeability for carrying out the in situ combustion procedure to be hereinafter described. It will be noted that the cement 17 holds tightly to the liner 16 and most of the adjacent pieces of the deposit 11 so that there is no continuous fluid passageway -along the side exterior surface of the liner 16. This is an advantage of merely uplifting the portion 23 until it disrupts the surface 12.

Another step of this method is the injecting of a combustion supporting fluid, such as air, into the lower extremity of the portion 23, and igniting the portion 23 receiving such fluid to pass a combustion front upwardly therethrough. Any means may be used to practice this step. Preferably, a tubing 24 is positioned within the liner 16 which is cleared of any debris resulting from the detonation of the explosives 14. The tubing 24 is sealed to the liner 16 by any suitable means such as filling the annulus between the liner 16 and the tubing 24 with a cement 26. A combustion supporting fluid may be injected downwardly through the tubing 24 into a cavity 27 formed by the explosives 14 within the portion 23. By igniting of the surrounding uplifted portion 23 of the deposit 11 receiving such injection of fluid, a combustion front can be propagated readily upwardly through such portion 23. By this means, an in situ combustion procedure may be practiced on the uplifted portion 23 of the deposit 11.

Preferably, the above steps are repeated to produce serially or simultaneously a plurality of adjacent uplifted portions 23 in the deposit 11. As is obvious, the well 13 may be provided with several different explosives 14, each positioned at a different depth, and such charges ignited in succession to greatly enlarge such uplifted portion 23. Referring to FIGURE 3, there is shown the well 13 and a like well 13 spaced therefrom which have been prepared by such mentioned steps. It will be apparent that the uplifted portion 23 produced from the wells 13 and 13 may be extended further in horizontal or vertical directions as desired. A header 28 is connected to the tubing 24 of the well 13 and also to tubing 24 of the well 13'. Through the header 28 is injected a combustion supporting fluid into the lower extremity of the uplifted portion 23 of the deposit 11. The uplifted portion 23 surrounding the cavities 27 of the `well 13 and similar cavity 27 of the well 13 is ignited by any suitable means. For example, a pyrophoric material, disposed in the cavities 27 and 27', can be ignited by the combustion supporting fluid introduced through the header 28. By this means a combustion front 29 is formed which passes radially outwardly and upwardly from the cavities 27 and 27 to in situ retort the hydrocarbons from the uplifted portion 23 of the deposit 11. During the continued injection of the combustion supporting fluid through the header 28, it will be apparent that the materials in the uplifted portion 23, particularly oil shales, will swell to close some of the openings between adjacent pieces. Such closing of these openings is an advantage in the present invention in that the combustion front 29 is forced to take alternative routes through the uplifted portion 23. Stated in another manner, the combustion front 29 has a propensity to pass through the openings in the uplifted portion 23 which offer the least amount of resistance to fluid flow and thereby preferentially heat the pieces of the deposit 11 adjacent such openings. Thus, as these preferentially heated pieces swell and restrict such openings, the combustion front 29 is forced to take another opening which offers the next least resistance to fluid flow. Thereupon, the procedure of swelling and taking of alternate routes of the combustion front 29 continues. The uplifting of the portion 23 has provided sufficient openings that a suflicient restriction of fluid flow therethrough caused by such swelling cannot terminate the combustion front 29. By this means, the retorted fluids readily are forced upwardly from the portion 23 to the surface of the earth.

In certain situations, such as where the pieces of the deposit 11 in the uplifted portion 23 are of large dimension, it is advantageous periodically to interrupt the injecting of the combustion supporting fluid through the header 28 to provide a heat soaking period. Such period provides for more uniformly distributing the heat from the combustion front 29 passing through the uplifted portion 23 of the deposit 11. Field tests have indicated that this period may extend up to at least several days in duration without oxygen flowing to the combustion front 29. Thereafter, the combustion front 29 can be re-initiated by again injecting the combustion supporting fluid through the header 28. This alternate injection and periodic interruption of the combustion supporting fluid allows the heat from the combustion front 29 to penetrate deeply into even the most thick pieces of the deposit 11 contained in the uplifted portion 23.

The soaking period is of additional advantage in that the retorted hydrocarbons which may condense as liquids in the unheated parts of the uplifted portion 23 will gravitate to the combustion front 29. These liquid hydrocarbons will then be subjected to hydrocracking in the combustion front 29. As a result of hydrocracking, the hydrocarbons expelled from the portion 23 are more readily pumpable fluids. A portion of the liquid hydrocarbons which have gravitated downwardly toward the lower parts of the portion 23 may be burned as fuel. This additional fuel source insures an adequate supply of heat for retorting even the most thick pieces of the deposit 11 contained in the uplifted portion 23.

Another step of the present method is the recovering of hydrocarbons from the fluids expelled by the combustion front 29 above the surface 12 of the deposit 11 from the portion 23. Any means for such hydrocarbon recovery from the expelled fluids may be used. However, it is an advantageous step of this invention to enclose the uplifted portion 23 of the deposit 11 which disrupts the surface 12 with a substantially impervious canopy 31 superimposed thereabove and sealed about its perimeter to the surface 12. The canopy 31 may be constructed of any substantially impermeable material to fluids. Preferably, the canopy 31 is constructed of light and inexpensive materials so that it may be readily moved from covering one uplifted portion to another upon cornpletion of the method of this invention. It is of particular advantage to construct the canopy 31 of a pliant film. The pliant film may be of materials such as polyethylene, mylar, poly-propylene, foils of aluminum, etc. Although films of these materials can be made into self-supporting structures, it is one feature of this invention that permits the canopy 31 to be made of a nonself-supporting film of these materials. A major portion of the hydrocarbons retorted by the combustion front 29 will be expelled ina fluid state at temperatures below 300 F. from the uplifted portion 23. Thus, the canopy 31 is not subjected to destructive temperatures. The canopy 31 is formed, as shown in FIGURE 3, of a large sheet of polyethylene lm of about 0.005 of an inch in thickness superimposed over the uplifted portion 23. The canopy 31 is sealed about its perimeter in substantially fluid-tight engagement to the undisturbed surface 12 of the deposit 11 by means of an anchor 32 formed of any suitable material. The canopy 31 should be of sufficient dimension that when inated it will extend above the uplifted portion 23 a sufficient distance to clear the header 28 and other apparatus disposed therebelow. A liquid removing gutter 33 is disposed about the interior perimeter of the canopy 31 adjacent the anchor 32. Another means to remove fluids collecting beneath the canopy 31 also is provided. Such means may take the form of an exhaust blower 34 extending through a duid-tight seal from the canopy 31. The header 2S also extends through a fluid-tight seal from the canopy 31. Thus, uids may be circulated from the header 23 upwardly through the uplifted portion 23 to collect, with fluids freed from the portion 23, beneath the canopy 31 and therefrom removed by the gutter 33 or the blower 34. The outlet of the Iblower 34 is connected to a suitable hydrocarbon recovery system which may include conventional oil and water separators. The gutter 33 may be also connected to this system. For convenience, such conventional systems are not shown in the drawings.

Where the canopy 31 is constructed of a pliant lm, the blower 34 is operated to remove a portion of the fluids collected below the canopy 31 at a rate adequate to maintain a pressure differential across the canopy 31 at values insuicient to destroy it. Preferably, the fluids collecting below the canopy 31 are removed initially at a rate suiiicient to inate the canopy 31 and thereby dispense with any required supporting structure to maintain the canopy 31 in its domelike position. This domelike position is of advantage as will be apparent hereinafter.

As a supplementary advantageous step, a fluid coolant is circulated across at least one surface of the canopy 31 to foster condensation of hydrocarbons on the interior surface 37 of the canopy 31. Such condensed hydrocarbons will flow downwardly along the surface 37 into the gutter 33 from whence they may be recovered by any suitable liquid handling system. It will `be apparent that the wind blowing across the exterior surfaces of the canopy 31 will provide this result as will a spray of water applied to this same surface. However, in the regions where oil shale and tar sands are found, water is relatively scarce and air cooling unreliable. For this reason, water preferably is sprayed onto the interior surface 37 of the canopy 31 for cooling the canopy 31. For this purpose, a spray head 38 connected to a pressurized water conduit 39 may be used. The spray of water from the head 38 runs downwardly along the interior surface 37 of the canopy 31 into the gutter 33 from where it will be recovered and recycled back to the water conduit 39. A1- ternatively, air or similar Huid may be blown across the interior surface 37 beneath the canopy 31 from a side opposite the blower 34. For this purpose, an air nozzle 41 extending through a fluid-tight seal into the canopy 31 may be used to supply a stream of air under suitable pressure to sweep the canopy 31 for cooling purposes. It will be apparent that during the periods of interrupting the injection of the com-bustion supporting fluid to the combustion front 29 to provide a heat soaking period, that the air through the nozzle 41 may be used to maintain iniiation of the canopy 31 when it is nonself-supporting.

In an alternative step, the rate of combustion supporting fluid injected through the header 28 is increased above the stoichiometric amount required to support the combustion front 29 suiciently to sweep the released hyrocarbons from the uplifted portion 23 in droplet form. Depending upon the, velocity of the combustion supporting fluid, the droplets may vary from a ne mist to those clearly visible. These droplets adhere to the canopy 31 and then flow down to the gutter 33 or they pass in a suspended form through the -blower 34 into the connected hydrocarbon recovery system where they can be recovered.

As the last step of this invention, the hydrocarbons collecting beneath the canopy 31 are recovered as liquids which condense and are caught in the gutter 33 or from the fiuids removed from beneath the canopy 31 by the blower 34.

After the uplifted portion 23 is retorted to a desired degree by the combustion front 29, the ilow of combustion supporting fluid through the header 28 is terminated. Thereafter, the canopy 31 may ybe released and then moved to enclose another uplifted portion of the deposit 11 desired to be retorted. Alternatively, the method may be extended to retort the deposit 11 at a greater depth by repeating the initial steps previously described.

From the foregoing it will be apparent that there has been provided a method well suited for satisfying all of the stated objects of this invention. Those skilled in the art will be able to make use of certain of the alternative steps in combination with the basic steps of this invention to obtain previously unobtainable results. Also, various changes may be made to the steps and to their order of this invention without departing from its scope or its intent. lt is intended that such changes, alterations, and modifications be encompassed within the scope of the appended claims, which claims contain the only limitations to be applied to this invention.

What is claimed is:

1. A method for recovering hydrocarbons from Ia carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a vertical distance within the deposit below the surface of the earth.

(b) detonating the explosives to uplift a portion of such deposit suciently to disrupt the surface of the earth thereabove as a result of the volume increase in such portion,

(c) enclosing the rubble mass in that portion of the deposit uplifted to disrupt the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealed to fluid ows about its perimeter to the earth,

(d) in situ retorting the rubble mass by injection of combustion supporting fluid thereinto at .a location spaced from the bottom of the rubble mass and ignition of the carbonaceous materials therein at said location for releasing hydrocarbons from the deposit, and

(e) recovering hydrocarbons from the fluids collecting in the rubble mass beneath the canopy.

2. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) from a location a vertical distance below the surface of the earth, upwardly arching the strata of the deposit with explosivelike suddenness over vertical displacements suicient to break vertically and horizontally said strata into fragments and to disrupt the surface of the earth thereabove so as t-o form a mass of rubble with -an increased volume sufficient to permit in situ retorting,

(b) enclosing the rubble mass in that portion of the deposit uplifted to disrupt the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealed about its perimeter to the earth,

(c) in situ retorting the rubble mass by injection of combustion supporting uid thereinto at a location spaced from the bottom of the rubble mass and ignition of the carbonaceous materials therein at said location for releasing hydrocarbons from the deposit, and

(d) recovering hydrocarbons from the uids collecting in the rubble mass beneath the canopy.

3. A method for recovering hydrocarbons from -a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a vertical distance within the deposit below the surface of the earth,

(b) detonatng the explosives to uplift a iportion of such deposit suflciently to disrupt the surface of the earth thereabove as a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit 'and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass a combustion front upwardly therethrough, and

(e) recovering hydrocarbons from the fluids collecting beneath the canopy.

4. A method for recovering hydrocarbons from a carbonaceous deposit 'adjacent the surface of the earth, comprising the steps of:

(a) uplifting a portion of the carbonaceous deposit until its volume increases and such uplifting disrupts the surface of the earth thereabove,

(b) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a superimposed canopy comprised of a substantially impermeable pliant lm and sealing the perimeter of the canopy to the earth,

(c) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass a combustion front upwardly therethrough,

(d) removing fluids collecting beneath the canopy at a rate suflicient initially to inflate the canopy and thereafter to maintain a pressure diiferential across the inflated canopy at values insufllcient to destroy such canopy, and

(e) recovering hydrocarbons from the fluids collecting beneath the canopy.

5. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a predetermined vertical distance within the deposit below the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit suiciently to disrupt the surface of the earth thereabove as -a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a superimposed canopy comprised of a substantially impermeable pliant film and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such iluid to pass a combustion upwardly therethrough,

(e) removing fluids collecting beneath the canopy at a rate suflcient initially to inflate the canopy and thereafter to maintain a pressure differential across the inated canopy at values insufllcient to destroy such canopy, and

(f) recovering hydrocarbons from the fluids collecting beneath the canopy.

6. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) uplifting a portion lof the carbonaceous deposit until its volume increases and such uplifting disrupts the surface ofthe earth thereabove,

(b) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealing the perimeter of the canopy to the earth,

(c) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass a combustion front upwardly therethrough,

(d) periodically interrupting the injection of the combustion supporting fluid to provide a heat soaking period for more uniformly distributing the heat from the combustion front through the uplifted portion of the deposit, and

(e) recovering hydrocarbons from the fluids collecting beneath the canopy.

7. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a predetermined vertical distance within the deposit below the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit suflicicntly to disrupt the surface of the earth thereabove as a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass a combustion front upwardly therethrough,

(e) periodically interrupting the injecting of the combustion supporting fluid to provide a heat soaking period for more uniformly distributing the heat from the combustion front through the uplifted portion of the deposit, and

(f) recovering hydrocarbons from the fluids collecting beneath the canopy.

8. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the arth, comprising the steps of (a) positioning explosives a predetermined vertical distance within the deposit below the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit sufficiently to disrupt the surface of the earth thereabove as a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a superimposed canopy comprised of a substantially impermeable pliant film and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass a combustion front upwardly therethrough,

(e) removing fluids collecting beneath the canopy at a rate sufficient initially to inflate the canopy and thereafter to maintain a pressure differential across the inflated canopy at values insufficient to destroy such canopy,

(f) periodically interrupting the injecting of the combustion supporting fluid to provide a heat soaking period for more uniformly distributing the heat from the combustion front through the uplifted portion of the deposit, and

(g) recovering hydrocarbons from the fluids collecting beneath the canopy.

9. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a vertical distance within the deposit below the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit sufficiently to disrupt the surface of the earth thereabove as a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a superimposed canopy comprised of a substantially impermeable pliant film and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass -a combustion front upwardly therethrough,

(e) removing lluids collecting beneath the canopy at a rate intially to inliate such canopy and thereafter -to maintain a pressure differential across the inliated canopy at values insuicient to destroy such canopy,

(f) circulating a fluid coolant across at least one surface of the canopy to foster hydrocarbon condensation on the interior surface of the canopy, and

(g) recovering hydrocarbons from the fluids collecting beneath the canopy.

10. The method of claim 9 wherein the coolant is water circulated across the interior surface of the canopy.

lll. The method of claim 9 wherein the coolant is air circulated across the interior surface of the canopy.

12. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) uplifting a portion of the carbonaceous deposit until its volume increases and such uplifting disrupts the surface of the earth thereabove,

(b) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealing the perimeter of the canopy to the earth,

(c) injecting la combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such liuid to pass a combustion front upwardly therethrough,

(d) injecting an excess of the combustion supporting fluid into the lower extremity of the uplifted portion of the deposit above the stoichiometric amount required to support combustion to sweep in droplet form released hydrocarbons from the uplifted portion, and

(e) recovering hydrocarbons from the fluids collecting beneath the canopy.

13. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a vertical distance within the deposit beneath the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit sufficiently to disrupt the surface of the earth thereabove as a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a substantially impermeable canopy superimposed thereabove and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fiuid to pass a combustion front upwardly therethrough,

(e) injecting an excess of the combustion supporting liuid into the lower extremity of the uplifted portion of the deposit -above the stoichiometric amount required to support combustion to sweep in droplet form released hydrocarbons from the uplifted portion, and

(f) recovering hydrocarbons from the liuids collecting beneath the canopy.

14. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a predetermined vertical distance within the deposit below the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit sufficiently to disrupt the surface of the earth thereabove as -a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a superimposed canopy comprised of a substantially impermeable pliant film and sealing the perimeter of the canopy to the earth,

(d) injecting la combustion supporting liuid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such fluid to pass a combustion front upwardly therethrough,

(e) removing fluids collecting beneath the canopy at a rate initially to inflate the canopy and thereafter to maintain a pressure differential across the inated canopy at values insufficient to destroy such canopy,

(f) periodically interrupting the injecting of the combustion supporting liuid to provide a heat soaking period for more uniformly distributing the heat from the combustion front through the uplifted portion of the deposit,

(g) injecting a liuid beneath the canopy during periods when injecting of the combustion of supporting fluid is interrupted to maintain its inflation, `and (h) recovering hydrocarbons from the fluids collecting beneath the canopy.

15. A method for recovering hydrocarbons from a carbonaceous deposit adjacent the surface of the earth, comprising the steps of:

(a) positioning explosives a predetermined vertical distance within the deposit below the surface of the earth,

(b) detonating the explosives to uplift a portion of such deposit sufficiently to disrupt the surface of the earth thereabove as `a result of the volume increase in such portion,

(c) enclosing the uplifted portion of the deposit disrupting the surface of the earth with a superimposed canopy comprised of a substantially impermeable pliant film -and sealing the perimeter of the canopy to the earth,

(d) injecting a combustion supporting fluid into the lower extremity of the uplifted portion of the deposit and igniting the carbonaceous deposit in such lower extremity of the uplifted portion receiving such liuid to pass a combustion front upwardly therethrough,

(e) removing fluids collecting beneath the canopy at la rate initially to inliate the canopy and thereafter to maintain a pressure differential across the infiated canopy at values insufficient to destroy such canopy,

(f) periodically interrupting the injection of the combustion supporting liuid to provide a heat soaking period for more uniformly distributing the heat from the combustion front through the uplifted portion of the deposit,

(g) injecting a fluid beneath the canopy during periods 1 1 when injecting of the combustion of supporting fluid is interrupted to maintain its ination,

(h) passing a liquid coolant across at least one surface of the canopy to foster hydrocarbon condensation on the interior surface of the canopy, Iand (i) recovering hydrocarbons from the fluids collecting beneath the canopy.

16. The method of claim 15 wherein the liquid coolant is Water.

17. The method of claim 15 wherein the liquid coolant is Water circulated across the interior surface of the canopy.

References Cited by the Examiner UNITED STATES PATENTS 2,853,137 9/1958 Marx et al. 166-11 5 2,874,777 2/1959 Tadema 166-11 2,946,382 7/1960 Tek et al 166-11 3,048,221 8/1962 Tek 166-11 CHARLES E. OCONNELL, Primary Examiner.

10 S. I. NOVOSAD, Assistant Examiner. 

1. A METHOD FOR RECOVERING HYDROCARBONS FROM A CARBONACEOUS DEPOSIT ADJACENT THE SURFACE OF THE EARTH, COMPRISING THE STEPS OF: (A) POSITIONING EXPLOSIVES A VERTICAL DISTANCE WITHIN THE DEPOSIT BELOW THE SURFACE OF THE EARTH. (B) DETONATING THE EXPLOSIVES TO UPLIFT A PORTION OF SUCH DEPOSIT SUFFICIENTLY TO DISRUPT THE SURFACE OF THE EARTH THEREABOVE AS A RESULT OF THE VOLUME INCREASE IN SUCH PORTION, (C) ENCLOSING THE RUBBLE MASS IN THAT PORTION OF THE DEPOSIT UPLIFTED TO DISRUPT THE SURFACE OF THE EARTH WITH A SUBSTANTIALLY IMPERMEABLE CONOPY SUPERIMPOSED THEREABOVE AND SEALED TO FLUID FLOWS ABOUT ITS PERIMETER TO THE EARTH, (D) IN SITU RETORTING THE RUBBLE MASS BY INJECTION OF COMBUSTION SUPPORTING FLUID THEREINTO AT A LOCATION SPACED FROM THE BOTTOM OF THE RUBBLE MASS AND IGINTION OF THE CARBONACEOUS MATERIALS THEREIN AT SAID LOCATION FOR RELEASING HYDROCARBONS FROM THE DEPOSIT, AND (E) RECOVERING HYDROCARBONS FROM THE FLUIDS COLLECTING IN THE RUBBLE MASS BENEATH THE CANOPY. 